When you take birth control pills, you’re putting a lot of faith into those tiny tablets. Naturally, you figure they’ll work because extensive scientific research has determined that they will.

But apparently, things can go wrong with the pills themselves—putting you at risk for an unintended pregnancy—which is what just happened in a scary new birth control recall.

Lupin Pharmaceuticals has announced a recall of chewable birth control pills, sold under the name Mibelas 24 F-E. According to the Food and Drug Administration, the pills were packaged in a way that reversed the order of the tablets—meaning, the first four pills were actually placebos instead of active tablets.

The FDA also points out that the reversed order may not be obvious to women, whether they’re new to taking the pill or have used it before, which increases the odds that the pills will be taken out of order.

"As a result of this packaging error, oral contraceptive tablets that are taken out of sequence may place the user at risk for contraceptive failure and unintended pregnancy," the FDA warns, adding that if a woman got pregnant on Mibelas 24 F-E, it could cause “significant adverse maternal or fetal health consequences, including death.” However, the FDA says, there have been no reports of this yet.

Women across the country are potentially impacted by this—the FDA says that the pills were distributed across the country to wholesalers, clinics, and pharmacies.

Lupin Pharmaceuticals is specifically recalling lot L600518, Exp 05/18 of Mibelas 24 Fe, and impacted packs will have four tablets with “LU” on one side and “M22” on the other first. (It should be 24 white or off-white tablets that have an “LU” and “N81” on them first.)

If you have one of the recalled versions of Mibelas 24 F-E, the FDA recommends that you return it to wherever you bought it from and contact your doctor if you have any concerns.